One day during the summer you and some friends make ice cream using an electric ice cream maker. To get the ice cream to form, a mixture of salt and ice is packed around the ice cream maker. A few days later you notice a yellow circle of dead grass where the ice cream maker had been placed. You hypothesize that some of the salt and ice mixture spilled onto the grass and ___.

Question

A.  froze the grass
B.  was isosmotic to the grass cells causing the yellow circle of dead grass
C.  was hyperosmotic to the grass cells causing the yellow circle of dead grass
D.  was hypoosmotic to the grass cells causing the yellow circle of dead grass

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
· What key words does the question contain and what do they mean?

Gather Content
· What do you know about osmotic concentration? How does it relate to the question?

Consider Possibilities
· What other information is related to the question? Which information is most useful?

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

C.  was hyperosmotic to the grass cells causing the yellow circle of dead grass


Clarify Question
· What is the key concept addressed by the question?
        o The question asks about osmotic concentration.
· What type of thinking is required?
        o You are being asked to analyze an observation and explain what happened to grass exposed to salt.
· What key words does the question contain and what do they mean?
        o Ice and salt – when making ice cream, salt is mixed with ice to make a super cooled solution that help the ice cream form.
        o Yellow circle of dead grass – this shows that where the salt and ice mixture came into contact with the grass, the grass was killed.

Gather Content
· What do you know about osmotic concentration? How does it relate to the question?
        o Plants are normally hyperosmotic to the water in the ground. This causes water to move into the plant cells through osmosis. When salt water comes into contact with the grass this process is reversed and water moves from the inside of the plant (lower salt concentration) to the ground (now with a higher salt concentration).

Consider Possibilities
· What other information is related to the question? Which information is most useful?
        o Hyperosmotic solutions would contain more salt than the cells, hyper is the root for more.
        o Hypoosmotic solutions would contain less salt than the cells, hypo is the root for less.
        o Isoosmotic solutions would contain the same salt concentration as the cells, iso is the root for same.

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o The salt and ice mixture has a higher concentration of salt than the grass cells, so it is hyperosmotic. The higher salt concentration pulls water from the grass, causing it to die.

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o This question asked you to analyze the observation that a salt and ice mixture caused grass to die and propose an explanation. If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you realize that it was the salt in the salt and ice mixture that was killing the grass? Did you understand that the ice and salt mixture was hyperosmotic relative to the grass cells?